/******************************************************************************
 * SAGE - Scalable Adaptive Graphics Environment
 *
 * Module: sageDoubleBuf.cpp
 * Author : Byungil Jeong
 *
 * Copyright (C) 2004 Electronic Visualization Laboratory,
 * University of Illinois at Chicago
 *
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following disclaimer
 *    in the documentation and/or other materials provided with the distribution.
 *  * Neither the name of the University of Illinois at Chicago nor
 *    the names of its contributors may be used to endorse or promote
 *    products derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Direct questions, comments etc about SAGE to bijeong@evl.uic.edu or 
 * http://www.evl.uic.edu/cavern/forum/
 *
 *****************************************************************************/

#include "sageDoubleBuf.h"
#include "sageBlock.h"

int sageDoubleBuf::init(sagePixelData **bufs)
{
   bufID = 0;
   blockBuf = bufs;

   bufLock = (pthread_mutex_t*)malloc(sizeof(pthread_mutex_t));
   pthread_mutex_init(bufLock, NULL);
   pthread_mutex_unlock(bufLock);
   notFull = (pthread_cond_t*)malloc(sizeof(pthread_cond_t));
   pthread_cond_init(notFull, NULL);
   notEmpty = (pthread_cond_t*)malloc(sizeof(pthread_cond_t));
   pthread_cond_init(notEmpty, NULL);

   return 0;
}//End of sageDoubleBuf()

sagePixelData* sageDoubleBuf::getBuffer(int id)
{ 
   if (id < 0 || id > 1) {
      sage::printLog("sageDoubleBuf::getBuffer : invalid buffer access");
      return NULL;
   }
      
   return blockBuf[id]; 
}

sagePixelData *sageDoubleBuf::getFrontBuffer()
{ 
   return blockBuf[bufID]; 
}  

sagePixelData* sageDoubleBuf::getBackBuffer()
{
   pthread_mutex_lock(bufLock);

   while(queueLen == 0) {
      //std::cerr << "=== waiting for new frames === " << std::endl;
      pthread_cond_wait(notEmpty, bufLock);
   }

   return blockBuf[1-bufID];
}

int sageDoubleBuf::bufSize()
{
   if (blockBuf)
      return (blockBuf[0]->getBufSize() * 2);
   
   sage::printLog("sageDoubleBuf::bufSize : buffers are not initialized");
   return -1;
}

int sageDoubleBuf::releaseBackBuffer()
{
   queueLen--;   
   pthread_mutex_unlock(bufLock);   

   if (queueLen == 0) {
      pthread_cond_signal(notFull);
   }   
   
   return 0;
}

int sageDoubleBuf::swapBuffer()
{
   pthread_mutex_lock(bufLock);
   
   while(queueLen > 0) {
      //std::cerr << "wait not full signal " << std::endl;
      pthread_cond_wait(notFull, bufLock);
   }

   bufID = 1 - bufID;
   //std::cout << "swap buffer" << std::endl;
     
   queueLen++;
   pthread_mutex_unlock(bufLock);
   pthread_cond_signal(notEmpty);

   firstFrameReady = true; 
   return 0;
}

int sageDoubleBuf::resendBuffer(int num)
{
   pthread_mutex_lock(bufLock);
   queueLen += num;
   pthread_mutex_unlock(bufLock);
   pthread_cond_signal(notEmpty);
      
   return 0;
}

sageDoubleBuf::~sageDoubleBuf()
{
   if (bufLock)
      free(bufLock);
   
   if (notFull)   
      free(notFull);
      
   if (notEmpty)
      free(notEmpty);
      
   if (blockBuf) {   
      if (blockBuf[0])
         delete blockBuf[0];

      if (blockBuf[1])
         delete blockBuf[1];
      
      delete [] blockBuf;
   }   
}//End of ~sageDoubleBuf()
